Note that the numbers 0 and 1 are constants defined as primitives of the
complex number axiom system (see df-07177 and df-17178).

Note: Only the digits 0 through 9 (df-07177
through df-97930) and the
number 10 (df-107931) are explicitly defined. Integers can be
exhibited
as sums of powers of 10 or as some other expression built from operations
on the numbers 0 through 10. For example, the prime number 823541 can be
expressed as . Decimals can be expressed as ratios of
integers, as in cos2bnd9706.

Most abstract math rarely requires numbers larger than 4. Even in Wiles'
proof of Fermat's Last Theorem, the largest number used appears to be 12.
Of course, there are exceptions. For larger numbers, base 4
representation has proved useful; see deccl8182 and the theorems that follow
it. See also 4001prm10200 (4001 is prime) and the proof of bpos13737.

A decimal representation of numbers may be added at some point in the
future if it is deemed useful. Ideas for a clean, eliminable definition
are welcome. (An awkward earlier definition was deleted from the database
on 18-Sep-1999.)